Parts | Days | Selection | Search | Downloads | Help
MS: Massenspektrometrie
MS 3: Laser Resonance Ionization Mass Spectrometry
MS 3.4: Talk
Tuesday, April 3, 2001, 16:45–17:00, EB 202
Gadolinium Ultra Trace Determination in Biomedical Samples by multi-step Laser Resonance Ionization MS — •Jochen Maul1, Klaus Blaum2, Christopher Geppert1, Peter Mueller1, Philipp Schumann1, Wolfgang Schreiber3, and Klaus Wendt1 — 1Institut fuer Physik, Universitaet Mainz, Germany — 2CERN, Geneva, Switzerland — 3Universitaetsklinik, Institut fuer Radiologie, Mainz, Germany
Diode Laser Based Resonance Ionization Mass Spectroscopy (RIMS) has been adapted for selective and sensitive ultra trace detection of rare earth elements. Following a detailed analysis of the optical excitation schemes in the spectrum of Gd I, first analytical investigations concern biomedical studies of Gadolinium-DTPA chelate which is used as the primary contrast medium for Magnetic Resonance Imaging (MRI). Triple resonance laser excitation is carried out on an atomic beam from a graphite furnace. Ionization via an autoionizing state results in a strong resonance enhancement of more than 105 providing high overall efficiency in combination with good isobaric selectivity. Ions are mass separated and detected with a quadrupole mass spectrometer (QMS). With an isobaric selectivity of higher than 108 and a detection efficiency of better than 10−6 we reached a detection limit of about 109 Gd atoms per sample corresponding to about 1 pg. Very good linearity and reproducibility over the full dynamical range of more than six orders of magnitude has been demonstrated. Recent investigations are performed to enhance the overall efficiency for cosmochemical investigations on Gd in meteoritegrains.